A screw machine is a machine tool in which a tool is selectively moved to engage a rotating workpiece.
A Davenport® multi-spindle automatic screw machine (Davenport® is a registered trademark of, and such machines are available from, Davenport Machine, Inc., 167 Ames Street, Rochester, N.Y. 14611) typically has five workpiece-holding spindles that are rotatably indexable from station to station. At each station, a tool is adapted to be selectively moved to engage the rotating workpiece held in the proximate spindle. Some tools are carried by tool arms that are pivotally mounted on the revolving head cap of the screw machine. These tool arms are adapted to be selectively moved relative to the head cap at each station to cause the particular tool held therein to perform a specific machining operation on the relatively-rotating workpiece.
In such Davenport® screw machines, a stationary spindle is commonly mounted on the machine in axially-spaced relation to a rotatable spindle mounted on an indexable head. This stationary tool may hold a drill, a mill, or the like, to perform an operation on the end of the relatively-rotating workpiece.
In such applications, it is desirable to provide a quick-change mechanism such that the tool can be quickly changed with a minimum of machine down-time. At the same time, it is highly desirable that the longitudinal axis of a tool held in the stationary spindle be aligned with the longitudinal axis of the rotatable spindle.
Accordingly, it would be generally desirable to provide an improvement in a Davenport® automatic screw machine that would allow a quick change of various tools, and that would allow the axis of the tool held in the stationary spindle to be aligned with the axis of a rotatable spindle.